In telecommunication systems of the kind mentioned above, more specifically in early care telephone systems, the subscribers, who are usually elderly with restricted mobility or otherwise disabled, have a need of being readily able to communicate, using their own telephone, with somebody who can quickly give them the help sought.
In systems where an automatic caller is used to ring, via the public telehpone network, a predetermined telephone number where a given function is to be automatically or manually executed, there are different known methods for getting the caller to select another telephone number if, for some reason, the first one cannot be answered. The systems may operate according to the following alternatives:
1. The caller is programmed for selecting another predetermined number at the next attempt at calling.
2. The call is answered and, via conventional call diverter equipment, is put through by ringing, via another telephone line, the telephone number where the function sought after can be provided.
3. The call is answered, and with the aid of a special signal the caller is directed to call up another predetermined telephone number.
4. The physical line is re-routed at the telephone exchange. The re-routing function is generally known as a diverter function.
The alternatives known to the prior art result in certain problems, however. Alternatives 1 and 3 require that the caller be programmed to ring the alternative telephone number. A change in the alternative number brings with it reprogramming of all the callers in the system. Alternative 2 requires expensive equipment, where it is required that two telephone subscribers are connected to the equiment. Alternative 4 requires switching equipment at the telephone exchange and extra wire pairs for controlling it.